We describe the patterns of composition and abundance of tree species and their relationships to environmental factors in an area affected by the Jirau hydroelectric dam on the Madeira River in the Brazilian state of Rondônia. Trees were sampled in 20 1-ha forest plots distributed among areas affected and unaffected by the hydroelectric reservoir. Predictors of species distribution included in the analyses were soil fertility (sum of bases) and texture, slope, and the vertical distance from the nearest drainage. We sampled 8504 individuals belonging to 909 species/morphospecies. Floristic differences occurred throughout the reservoir area and between the sides of the river, and were strongly associated with edaphic and geological factors. The predictor with the greatest effect on the floristic changes was the sum of bases, coupled with the vertical distance from the nearest drainage, the latter reflecting the influence of the riparian zone. The forests sampled were heterogeneous and included transitional formations between unflooded terra firme and seasonally inundated (varzea, campinarana) forests. Although a considerable number of species (253) were restricted to plots affected by the reservoir, most of these species have a widespread distribution in the Amazon region. However, conservation measures are required in order to preserve species associations and ecosystems processes similar to those most affected by the reservoir such as the river floodplains. Our study reinforces the need to consider the heterogeneity of habitats affected by reservoirs when making decisions concerning the building of hydroelectric dams in the Amazon.Abstract in Portuguese is available in the online version of this article.

1. Forest responses to changes in drought frequency is a critical matter for the future of Amazon forests under climate change, but equally important is the much less studied response to large floods, which may also increase tree mortality and change forest functionality. Further, forest vulnerability to flood is being exacerbated by large hydroelectric dams on Amazon rivers that put upland environments not adapted to flood at unique risk.2. To address this critical knowledge gap, we evaluated the effects of the extreme 2014 rainfall coupled with the newly constructed Jirau hydroelectric dam on tree survival and forest functionality, in the upper Madeira River basin. We used surveys of campinarana white-sand forests (stems >1 cm in seven 1 ha plots) conducted before and after the extreme flood to test trait-based ecological theory predictions of the impact of flood on overall community function.3. We found that flooding increased mortality by nearly five-fold (from 3.2% to 15.1%), mostly in smaller trees. This large mortality induced significant and consistent shifts in community function, towards species with conservative life strategies: direct comparison of trait differences between surviving and dying trees showed that survivors had smaller, high density stomata, and higher leaf dry matter content, wood density and root tissue density (RTD). Size and density of stomata and RTD were the most important predictors of species mortality rates. Synthesis and applications.Although focused on a single event in one type of forest, this work highlights the general importance, and need for further study, of interaction between climate change and mega-dams in Amazon forests. In particular, we expect that continued expansion of hydroelectric dams in Amazonia will likely intensify the impact of large floods on forests made newly vulnerable by these dams, with substantial effect on future forest functionality in expanded floodplain areas across the Basin. Hence, these interaction analyses should be required in the Brazilian legal instruments such as the environmental impact assessments and its accompanying Environmental Impacts Reports for large infrastructure projects in Amazon.in the functional composition of these forests towards more slowgrowing plants, which, on the one hand, would make campinaranas more resilient in the event of new floods, but could, on the other hand, decrease its short-term capacity for carbon sequestration besides lowering forest richness and diversity. We herein followed the K E Y W O R D S dams, flood tolerance, functional traits, global warming, precipitation anomaly, root tissue density, stomata density, tree mortality | 2643

Regeneração e estrutura populacional de jatobá-da-mata (Hymenaea courbaril L.), em dois fragmentos com diferentes graus de perturbação antrópica RESUMO(Regeneração e estrutura populacional de jatobá-da-mata (Hymenaea courbaril L.), em dois fragmentos com diferentes graus de perturbação antrópica). O objetivo do estudo foi avaliar a estrutura populacional e os efeitos da intensidade luminosa no recrutamento de jatobá-da-mata (Hymenaea courbaril L.) em dois fragmentos de Mata de Galeria não-inundável, com diferentes graus de perturbação antrópica. Foi assumida a hipótese de que as populações diferem nas classes de tamanho (diâmetro e altura) e abundância dos indivíduos entre os fragmentos e o recrutamento responde às diferenças de luminosidade disponível no sub-bosque. Como espécie clímax dependente de luz amplamente distribuída e adaptada a ambientes heterogêneos, espera-se uma maior abundância e regeneração de jatobá-da-mata no fragmento com maior incidência luminosa. Em cada fragmento foram utilizadas 25 parcelas permanentes, alocadas de forma aleatória ao longo de transectos entre a borda da mata e o leito córrego posicionados perpendicularmente à margem do córrego. As plântulas foram amostradas no interior de cada parcela, a partir de quatro sub-parcelas de 2x2 m ao longo de uma linha central no comprimento da parcela. No sub-bosque, em cada sub-parcela, a radiação fotossinteticamente ativa foi determinada e os valores de transmitância (T%) foram obtidos a partir das medidas a pleno sol fora da mata. Nos dois fragmentos o maior número de indivíduos se concentrou nas menores classes de tamanho, mas não foi obtido um bom ajuste à distribuição exponencial negativa (J invertido ABSTRACT(Regeneration of Hymenaea courbaril L. in two forest fragments with diff erent degrees of human impact). Th e objective of this research was to study the population structure of Hymenaea courbaril in two fragments of non-fl ooded gallery forests with diff erent degrees of human impact. Th e research hypothesis was that populations present diff erent size classes and number of individuals between fragments and that recruitment is related to understory light. As a climax species that requires light, and a species that is adapted to a variety of environments, there would probably be a higher abundance and regeneration of H. courbaril in a fragment that has more light. Twenty-fi ve plots (10 x 20 m) were set in two fragments using transects between the forest edge and the stream bank. Th e seedlings were recorded within each plot by means of four subplots (2 x 2 m) in a central line along the plots. Within the understory the photosynthetic active radiation was determined and the transmittance values (T%) were calculated by measuring the sunlight in an open fi eld. In both fragments, more individuals were concentrated in the smaller size classes. However the population sizes in both fragments were not adjusted to the negative exponential distribution (reversed J curve). A linear regression analysis indicated that both the diameter and ...

This study provides a checklist of the phanerogams and pteridophytes of the Tocantins river middle basin, in northern Goiás state and southern Tocantins state, Brazil. Herbarium samples were collected from 2000 to 2009 and this floristic survey recorded 1572 species from 135 families. The most species-rich families were Fabaceae (217), Poaceae (116), Asteraceae (88), Euphorbiaceae (65), Orchidaceae (58) and Malpighiaceae (56). Furthermore, 14 endangered species and 31 rare species were recorded, mainly associated with the campos rupestres in the Veadeiros Plateau region. The flora mainly from the phytophyisiognomies cerrado stricto sensu, campo rupestre (“rocky fields”), mata de galeria (“gallery forest”), mata ciliar (“riverine forest”) and semi-deciduous seasonal forest comprised typical species of the mid-western Cerrado floristic province, such as the most widely known woody plants Anadenanthera colubrina (Vell.) Brenan (popular name angico), Aspidosperma subincanum Mart. ex A. DC. (guatambú), Astronium fraxinifolium Schott ex Spreng. (gonçalo-alves), Callisthene fasciculata Mart. (pau-jacaré), Dipteryx alata Vogel (barú), Guazuma ulmifolia Lam. (mutamba) and Magonia pubescens A. St.-Hil. (tingui). This study is the first to record a wide floristic list of this important region of central Brazil.

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As árvores nas cidades trazem benefícios como melhorias na paisagem, proporcionando ambientes que favorecem o convívio social e a relação do homem com a natureza, assim como o equilíbrio entre as áreas verdes e o concreto encontrado nas cidades. Porém, uma arborização com a utilização de espécies inadequadas ao espaço urbano, como as de porte muito grande ou susceptível aos ventos, pode trazer problemas, como a queda de árvores ou de grandes galhos, que causam prejuízos materiais e acidentes. Este estudo foi realizado no Centro de Ciências Agroveterinárias (CAV) da Universidade do Estado de Santa Catarina (UDESC) em Lages, SC, e objetivou conhecer a composição florística da arborização urbana do campus e avaliar os danos causados às árvores após uma tempestade com ventos intensos. A arborização do CAV-UDESC é composta por 791 indivíduos distribuídos em 39 espécies nativas e exóticas, sendo que os gêneros com maior número de indivíduos foram Eucalyptus e Pinus. Algumas espécies foram mais danificadas pela ação das rajadas intensas de ventos, entre elas Cupressus lusitanico, recomendando-se evitar a sua utilização na arborização urbana.